AxibugEmuOnline/Core/VirtualNes.Core/Mapper/Mapper009.cs

//////////////////////////////////////////////////////////////////////////
// Mapper009  Nintendo MMC2                                             //
//////////////////////////////////////////////////////////////////////////
using static VirtualNes.MMU;
using BYTE = System.Byte;


namespace VirtualNes.Core
{
    public class Mapper009 : Mapper
    {
        BYTE[] reg = new byte[4];
        BYTE latch_a, latch_b;

        public Mapper009(NES parent) : base(parent) { }

        public override void Reset()
        {
            SetPROM_32K_Bank(0, PROM_8K_SIZE - 3, PROM_8K_SIZE - 2, PROM_8K_SIZE - 1);

            reg[0] = 0; reg[1] = 4;
            reg[2] = 0; reg[3] = 0;

            latch_a = 0xFE;
            latch_b = 0xFE;
            SetVROM_4K_Bank(0, 4);
            SetVROM_4K_Bank(4, 0);

            nes.ppu.SetChrLatchMode(true);
        }

        //void Mapper009::Write(WORD addr, BYTE data)
        public override void Write(ushort addr, byte data)
        {
            switch (addr & 0xF000)
            {
                case 0xA000:
                    SetPROM_8K_Bank(4, data);
                    break;
                case 0xB000:
                    reg[0] = data;
                    if (latch_a == 0xFD)
                    {
                        SetVROM_4K_Bank(0, reg[0]);
                    }
                    break;
                case 0xC000:
                    reg[1] = data;
                    if (latch_a == 0xFE)
                    {
                        SetVROM_4K_Bank(0, reg[1]);
                    }
                    break;
                case 0xD000:
                    reg[2] = data;
                    if (latch_b == 0xFD)
                    {
                        SetVROM_4K_Bank(4, reg[2]);
                    }
                    break;
                case 0xE000:
                    reg[3] = data;
                    if (latch_b == 0xFE)
                    {
                        SetVROM_4K_Bank(4, reg[3]);
                    }
                    break;
                case 0xF000:
                    if ((data & 0x01) != 0) SetVRAM_Mirror(VRAM_HMIRROR);
                    else SetVRAM_Mirror(VRAM_VMIRROR);
                    break;
            }
        }

        //void Mapper009::PPU_ChrLatch(WORD addr)
        public override void PPU_ChrLatch(ushort addr)
        {
            if ((addr & 0x1FF0) == 0x0FD0 && latch_a != 0xFD)
            {
                latch_a = 0xFD;
                SetVROM_4K_Bank(0, reg[0]);
            }
            else if ((addr & 0x1FF0) == 0x0FE0 && latch_a != 0xFE)
            {
                latch_a = 0xFE;
                SetVROM_4K_Bank(0, reg[1]);
            }
            else if ((addr & 0x1FF0) == 0x1FD0 && latch_b != 0xFD)
            {
                latch_b = 0xFD;
                SetVROM_4K_Bank(4, reg[2]);
            }
            else if ((addr & 0x1FF0) == 0x1FE0 && latch_b != 0xFE)
            {
                latch_b = 0xFE;
                SetVROM_4K_Bank(4, reg[3]);
            }
        }

        //void Mapper009::SaveState(LPBYTE p)
        public override void SaveState(byte[] p)
        {
            p[0] = reg[0];
            p[1] = reg[1];
            p[2] = reg[2];
            p[3] = reg[3];
            p[4] = latch_a;
            p[5] = latch_b;
        }

        //void Mapper009::LoadState(LPBYTE p)
        public override void LoadState(byte[] p)
        {
            reg[0] = p[0];
            reg[1] = p[1];
            reg[2] = p[2];
            reg[3] = p[3];
            latch_a = p[4];
            latch_b = p[5];
        }

        public override bool IsStateSave()
        {
            return true;
        }
    }
}